1. Field of the Invention
This invention relates to a process for improving the quality including sugar content of fruit which comprises applying alginic acid oligosaccharide(s) to a fruit tree in order to produce more delicious fruit.
2. Description of the Prior Art
The production and shipping of various fruits such as tangerine (Citrus Unshiu) in Japan amount to six million tons per year.
The deliciousness of fruit significantly varies among varieties. Therefore it has been vigorously attempted to improve fruit plants in order to produce highly delicious fruit. However, plant breeding requires a great deal of efforts and a prolonged period of time. Further, a fruit variety, which would exhibit a "deliciousness" under specific cultivation conditions including sunshine hours, photoperiod, atmospheric temperature and rainfall, would fail to exhibit the "deliciousness" unless it is grown under appropriate conditions. Thus it is difficult to produce "delicious" fruit on a nationwide scale in Japan where the climate shows considerable variations. The "deliciousness" of fruit would generally depend on the sugar content thereof. The necessary sugar content for each fruit has been determined through organoleptic tests. For example, the lower limit of the sugar content in fruit which are regarded as delicious is 11.0 for tangerine, 12.5 for apple, 16.0 for persimmon, 15.0 for grape, 11.0 for melon, 10.0 for orange, and 9.0 for grapefruit. The sugar content as used herein is expressed as a Brix degree measured with a sugar refractometer, with cane sugar being taken as a standard.
It can also be expected to enhance "deliciousness" by lowering the content of an organic acid such as citric acid.